Multi option rebuilding in a dispersed storage network

ABSTRACT

A method includes identifying an encoded slice for rebuilding. The method further includes determining whether the set of encoded slices is stored in an encrypted section of a vault or within an unencrypted section of the vault. The method further includes, when the set of encoded slices is stored in the unencrypted section of the vault, determining whether the set of storage units have viewing rights. The method further includes, when the set of storage units does not have the viewing rights, enabling a restricted rebuilding process to rebuild the encoded slice. The method further includes, when the set or storage units does have the viewing rights, enable an unrestricted rebuilding process to rebuild the encoded slice.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application also claims prioritypursuant to 35 U.S.C. § 120 as a continuation of U.S. Utility patentapplication Ser. No. 15/264,160, entitled “MULTI OPTION REBUILDING IN ADISPERSED STORAGE NETWORK,” filed Sep. 13, 2016, pending, which claimspriority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional ApplicationNo. 62/248,636, entitled “SECURELY STORING DATA IN A DISPERSED STORAGENETWORK”, filed Oct. 30, 2015, both of which are hereby incorporatedherein by reference in their entirety and made part of the present U.S.Utility Patent Application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

Within a cloud storage system, self-healing or rebuilding of lost orcorrupted data elements is an important aspect for reliable datastorage. For example, when a disk drive fails, the data it stores islost but can be recreated from other data. As a specific example, in adispersed storage system that uses error correction, data is encodedinto a plurality of encoded data pieces (e.g., n pieces) of which, anycombination of “m” encoded data pieces is sufficient to reconstruct thedata. As such, when an encoded data piece is lost, it can be recreatedby recovering the data and re-encoding the data to reproduce the “n”encoded data pieces, which includes a new copy of the lost encoded datapiece.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of vaults storingencoded data slices in accordance with the present invention;

FIG. 10 is a schematic block diagram of an embodiment of vaults spanningone or more storage pools in accordance with the present invention;

FIG. 11 is a schematic block diagram of an embodiment of a device inaccordance with the present invention;

FIG. 12 is a logic diagram of an example of a method of multi optionrebuilding in accordance with the present invention;

FIG. 13 is a logic diagram of another example of a method of multioption rebuilding in accordance with the present invention;

FIG. 14 is a diagram of an example of restricted rebuilding inaccordance with the present invention; and

FIG. 15 is a logic diagram of another example of a method of multioption rebuilding in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 and 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data (e.g., data 40) as subsequently described withreference to one or more of FIGS. 3-8. In this example embodiment,computing device 16 functions as a dispersed storage processing agentfor computing device 14. In this role, computing device 16 dispersedstorage error encodes and decodes data on behalf of computing device 14.With the use of dispersed storage error encoding and decoding, the DSN10 is tolerant of a significant number of storage unit failures (thenumber of failures is based on parameters of the dispersed storage errorencoding function) without loss of data and without the need for aredundant or backup copies of the data. Further, the DSN 10 stores datafor an indefinite period of time without data loss and in a securemanner (e.g., the system is very resistant to unauthorized attempts ataccessing the data).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The managing unit 18 creates and stores user profile information (e.g.,an access control list (ACL)) in local memory and/or within memory ofthe DSN memory 22. The user profile information includes authenticationinformation, permissions, and/or the security parameters. The securityparameters may include encryption/decryption scheme, one or moreencryption keys, key generation scheme, and/or data encoding/decodingscheme.

The managing unit 18 creates billing information for a particular user,a user group, a vault access, public vault access, etc. For instance,the managing unit 18 tracks the number of times a user accesses anon-public vault and/or public vaults, which can be used to generate aper-access billing information. In another instance, the managing unit18 tracks the amount of data stored and/or retrieved by a user deviceand/or a user group, which can be used to generate a per-data-amountbilling information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. The dispersed storage error encodingparameters include an encoding function (e.g., information dispersalalgorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment (i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment,and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides the data(e.g., a file (e.g., text, video, audio, etc.), a data object, or otherdata arrangement) into a plurality of fixed sized data segments (e.g., 1through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more).The number of data segments created is dependent of the size of the dataand the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 80 is shown inFIG. 6. As shown, the slice name (SN) 80 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a schematic block diagram of an example of vaults (e.g., 1 and2) storing pluralities of sets of encoded data slices. Each plurality 82of sets of encoded data slices (EDSs) corresponds to the encoding of adata object, a portion of a data object, or multiple data objects, wherea data object is one or more of a file, text, data, digital information,etc. For example, the highlighted plurality of encoded data slicescorresponds to a data object having a data identifier of “a2”.

Each encoded data slice of each set 80 of encoded data slices isuniquely identified by its slice name, which is also used as at leastpart of a logical DSN address for storing the encoded data slice. Asshown, a set of EDSs includes EDS 1_1_1_a1 through EDS 5_1_1_a1. The EDSnumber includes pillar number, data segment number, vault ID, and dataobject ID. Thus, for EDS 1_1_1_a1, it is the first EDS of a first datasegment of data object “a1” and is to be stored, or is stored, in vault1.

As is further shown, another plurality of sets of encoded data slicesare stored in vault 2 for data object “b1”. There are Y sets of EDSs,where Y corresponds to the number of data segments created by segmentingthe data object. The last set of EDSs of data object “b1” includes EDS1_Y_2_b1 through EDS 5_Y_2_b1. Thus, for EDS 1_Y_2_b1, it is the firstEDS of the last data segment “Y” of data object “b1” and is to bestored, or is stored, in vault 2.

A vault is a logical memory container supported by the storage units ofthe DSN and is allocated to store data for one or more user computingdevices. A vault (e.g., vault 1) may include an unencrypted section 84and an encrypted section 86. The encrypted section 86 stores encodeddata slices that have been encrypted using one or more encryption keys.For example, a first data segment of data object “a1” is dispersedstorage error encoded to produce a set of unencrypted encoded dataslices set 80 (note that the first data segment may or may not beencrypted prior to the error encoding). Each unencrypted encoded dataslice is encrypted using an encryption key (e.g., a shared encryptionkey, a unique encryption key for each slice, or a combination thereof).The resulting set of encrypted encoded data slices is stored in theencryption section 86 as a set 80 of EDSs.

The encryption key (e.g., shared, unique, or combination) is dispersedstorage error encoded to produce a set 86 of encoded key slices, whichis stored in the unencrypted section 84. Unless authorized by a DSNmanaging device, a trusted authority device, or other administrativedevice, each of the storage units supporting the vault (e.g., vault 1)does not have access to enough encoded key slices to recreate theencryption key (e.g., each storage unit has access to one encoded keyslice). As such, the storage units do not have viewing rights to theencoded data slices (i.e., cannot decrypt the encoded data slices).Accordingly, any unauthorized access of a storage unit will not revealany useful information about the encoded data slices, data segments,data objects, and/or computing devices authorized to access the data(e.g., read, write, edit, delete, etc.).

FIG. 10 is a schematic block diagram of an example of vaults spanningmultiple storage pools. In this example, the DSN memory 22 includes aplurality of storage units 36 arranged into a plurality of storage pools(e.g., 1-n). Further, each storage pool includes seven storage units forease of illustration. A storage pool, however, can have many morestorage units than seven and, from storage pool to storage pool, mayhave different numbers of storage units.

The storage pools 1-n support two vaults (vault 1 and vault 2) usingonly five of the seven of storage units. The number of storage unitswithin a storage pool supporting a vault corresponds to the pillar widthnumber, which is five in this example. Note that a storage pool may haverows of storage units, where SU #1 represents a plurality of storageunits, each corresponding to a first pillar number; SU #2 represents asecond plurality of storage units, each corresponding to a second pillarnumber; and so on. Note that other vaults may use more or less than apillar width number of five storage units.

FIG. 11 is a schematic block diagram of an embodiment of a device 90that includes the computing core 26 and a rebuilding module 92. Thedevice 90 is one or more of computing device 12, computing device 16,managing unit 18, integrity processing unit 20, and storage unit 36. Therebuilding module 92 is a module operable with the device to perform oneor more of the functions described in one or more of FIGS. 12-15.

FIG. 12 is a logic diagram of an example of a method of multi optionrebuilding that begins at step 100 where the rebuilding module of adevice identifies an encoded slice for rebuilding, which may be done ina variety of ways. For example, the device receives a request to rebuildthe encoded slice. As another example, the device determines that theencoded slice requires rebuilding because its revision level is wrong.As another example, the device determines that the encoded slicerequires rebuilding because the storage unit storing the encoded slicedid not response to a request regarding the encoded slice. As a furtherexample, the device determines that the encoded slice requiresrebuilding because its calculated integrity information does not matchstored integrity information for the encoded slices.

The encoded slice is from a set of encoded slices that is created bydispersed storage error encoding a data element. In an example, the dataelement includes an encryption key that is used to encrypt data (e.g.,one or more data segments of a data object) stored in the encryptedsection of the vault. The encryption key is dispersed storage errorencoded into a set of encoded key slices that is stored in theunencrypted section of the vault. As another example, the data elementis a data segment of a data object that is dispersed storage errorencoded into a set of encoded data slices. The set of encoded dataslices is encrypted using an encryption key to produce an encrypted setof encoded data slices that is stored in the encrypted section of thevault. In yet another example, the data element is a data segment of adata object, wherein the data segment is dispersed storage error encodedinto a set of encoded data slices that is stored in the unencryptedsection of the vault supported by the set of storage units.

The method continues at step 102, where the rebuilding module determineswhether the set of encoded slices is stored in an encrypted section of avault or within an unencrypted section of the vault. When the set ofencoded slices is stored in the unencrypted section of the vault, themethod continues at step 104 where the rebuilding module determines(e.g., by default, by a look up, by instruction, etc.) whether the setof storage units have viewing rights (i.e., rights to see the data inits unencrypted form) for encoded data slices stored in the encryptedsection.

When the set of storage units does not have the viewing rights, themethod continues at step 106 where the rebuilding module enables arestricted rebuilding process to rebuild the encoded slice. An exampleof the restricted rebuilding process is discussed with reference toFIGS. 13 and 14.

When the set or storage units does have the viewing rights or when theset of encoded slices is stored in the encrypted section of the vault,the method continues at step 108 where the rebuilding module enables anunrestricted rebuilding process to rebuild the encoded slice. An exampleof the unrestricted rebuilding process is discussed with reference toFIG. 15.

If, while processing the rebuilding of the encoded slice, the rebuildingmodule identifies a second encoded slice of the set of encoded slicesfor rebuilding (i.e., the same set as the encoded slice being rebuiltand in a different storage unit of the set of storage units), therebuilding module uses the determination of whether the set of storageunits have viewing rights to the set of encoded slices. When the set ofstorage units does not have the viewing rights, the rebuilding moduleenables the restricted rebuilding process to rebuild the encoded sliceand the second encoded slice in a sequential manner (i.e., therebuilding of the second encoded slice does not commence until therebuilding of the encoded slice is complete). When the set of storageunits do have the viewing rights, the rebuilding module enables theunrestricted rebuilding process to rebuild the encoded slice and thesecond encoded slice substantially concurrently.

FIG. 13 is a logic diagram of another example of a method of restrictedrebuilding that begins at step 110 where the rebuilding module sends apartial rebuilding request to a subset of storage units of the storageunits (e.g., at least a decode threshold number). Note that the subsetof storage units does not include the first storage unit, which isassigned to store the encoded slice being rebuilt. The method continuesat step 112 where the storage units in the subset of storage unitsexecute a partial rebuilding function for the encoded slice to producepartial slice rebuilding data. An example of creating the partial slicerebuilding data is discussed with reference to FIG. 14. The methodcontinues at step 114 where the storage units send their respectivepartial slice rebuilding data to the rebuilding module. The rebuildingmodule receives the set of partial slice rebuilding data and generatestherefrom a rebuilt encoded slice.

FIG. 14 is a diagram of an example of a storage unit generating itspartial slice rebuilding information in accordance with the restrictedrebuilding function. This example assumes that encoded data slice EDS3_1 is to be rebuilt. Accordingly, three of storage units 1, 2, 4, and 5will generate partial slice rebuilding data. This example is from theperspective of storage unit 1, which stores encoded data slice EDS 1_1.Storage unit 1 performs a two-step process to generate the partial slicerebuilding data. In the first step, the storage unit performs a partialdecoding of the encoded data slice EDS 1_1 using selected rows of thedecoding matrix. This produces a partial decode matrix, which isillustrated to include x₁S1_1; x₂S1_1; and x₃S1_1. x₁, x₂, and x₃ arecoefficients of the decoding matrix and S1_1 corresponds to the encodeddata slice EDS 1_1.

The storage unit then performs a partial encoding step by matrixmultiplying the partial decode matrix with a reduced encode matrix (E)to produce the partial slice rebuilding data. The reduced encoded matrixis reduced to a single row that corresponds to the row of the fullencoded matrix that created encoded data slice EDS 3_1 (i.e., the onebeing rebuilt). In this example, the coefficients of the relevant roware g, h, and i, such that the first partial slice rebuilding data maybe expressed in Gaussian Field as g*x₁S1_1+h*x₂S1_1+i*x₃S1_1.

The rebuilding module receives the partial slice rebuilding data fromthree storage units in this example. The rebuilding module performs afunction on the set of partial slice rebuilding data to generate therebuilt encoded data slice (EDS 3_1). For example, the rebuilding moduleperforms an exclusive OR function on the set of partial slice rebuildingdata to generate the rebuilt encoded data slice. For a more detaileddiscussion of partial rebuilding refer to issued patent entitled “METHODAND APPARATUS FOR SLICE PARTIAL REBUILDING IN A DISPERSED STORAGENETWORK” having a U.S. Pat. No. 8,706,980.

FIG. 15 is a logic diagram of another example of a method ofunrestricted rebuilding that begins at step 120 where the rebuildingmodule sends slice retrieval requests to a subset of storage units ofthe storage units (e.g., at least a decoded threshold number of storageunits), which does not include the storage unit that stores the encodedslice in need of rebuilding. In response to the slice retrievalrequests, the method continues at step 122 where the rebuilding modulereceives a subset of encoded slices of the set of encoded slices fromthe subset of storage units (e.g., a decode threshold number of encodedslices, which does not include the encoded slice in need of rebuilding).

The method continues at step 124 where the rebuilding modulereconstructs the data element (e.g., a data segment, an encryption key)from the subset of encoded slices. The method continues at step 126where the rebuilding module dispersed storage error encodes thereconstructed data element to produce a new set of encoded slices. Themethod continues at step 128 where the rebuilding module selects one ofthe new set of encoded data slices as rebuilt encoded slice for theencoded slice (e.g., selects new EDS 3_1 as a rebuild slice for EDS3_1).

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A computing device comprising: an interfaceconfigured to interface and communicate with a dispersed or distributedstorage network (DSN); memory that stores operational instructions; andprocessing circuitry operably coupled to the interface and to thememory, wherein the processing circuitry is configured to execute theoperational instructions to: identify, via the interface, an encodeddata slice (EDS) to be rebuilt, wherein a data object is segmented intoa plurality of data segments, wherein a data segment is dispersedstorage error encoded to produce a set of encoded data slices (EDSs),which includes the EDS, wherein a set of storage units (SUs) of the DSNstores the set of EDSs, and wherein a first storage unit (SU) of the setof SUs is assigned to store the EDS; determine whether the set of EDSsis stored in an encrypted section of a vault or within an unencryptedsection of the vault; based on a first determination that the set ofEDSs is stored in the encrypted section of the vault, enable anunrestricted rebuilding process to rebuild the EDS; based on a seconddetermination that the set of EDSs is stored in the unencrypted sectionof the vault, determine whether the set of SUs have viewing rights; andbased on a third determination that the set of SUs does not have theviewing rights, enable a restricted rebuilding process to rebuild theEDS.
 2. The computing device of claim 1, wherein the processingcircuitry is further configured to execute the operational instructionsto: based on a fourth determination that the set of SUs does have theviewing rights, enable the unrestricted rebuilding process to rebuildthe EDS.
 3. The computing device of claim 1, wherein the data objectcomprises: an encryption key that is used to encrypt data stored in theencrypted section of the vault, wherein the encryption key is dispersedstorage error encoded into a set of encoded key slices that is stored inthe unencrypted section of the vault supported by the set of SUs.
 4. Thecomputing device of claim 1, wherein the set of EDSs is encrypted usingan encryption key to produce an encrypted set of EDSs that is stored inthe encrypted section of the vault supported by the set of SUs.
 5. Thecomputing device of claim 1, wherein the set of EDSs is stored in theunencrypted section of the vault supported by the set of SUs.
 6. Thecomputing device of claim 1, wherein, in accordance with theunrestricted rebuilding process to rebuild the EDS, the processingcircuitry is further configured to execute the operational instructionsto: send slice retrieval requests to a subset of SUs of the set of SUs,wherein the subset of SUs excludes the first SU; in response to theslice retrieval requests, receive a subset of EDSs of the set of EDSsfrom the subset of SUs; reconstruct the data segment from the subset ofEDSs to generate a reconstructed data segment; dispersed storage errorencode the reconstructed data segment to produce a new set of EDSs; andselect one of the new set of EDSs as a rebuilt EDS for the EDS.
 7. Thecomputing device of claim 1, wherein the processing circuitry is furtherconfigured to execute the operational instructions to: identify a secondEDS of the set of EDSs to be rebuilt; based on the third determinationthat the set of SUs does not have the viewing rights: enable therestricted rebuilding process to rebuild the EDS; and when therebuilding of the EDS is complete, enable the restricted rebuildingprocess to rebuild the second EDS; and based on a fourth determinationthat the set of SUs does have the viewing rights, enable theunrestricted rebuilding process to rebuild the EDS and the second EDSsubstantially concurrently.
 8. The computing device of claim 1, wherein:a decode threshold number of EDSs are needed to recover the datasegment; a read threshold number of EDSs provides for reconstruction ofthe data segment; a write threshold number of EDSs provides for asuccessful storage of the set of EDSs within the DSN; the set of EDSs isof pillar width and includes a pillar number of EDSs; and each of thedecode threshold number, the read threshold number, and the writethreshold number is less than the pillar number.
 9. The computing deviceof claim 1 further comprising: a wireless smart phone, a laptop, atablet, a personal computers (PC), a work station, or a video gamedevice.
 10. The computing device of claim 1, wherein the DSN includes atleast one of a wireless communication system, a wire lined communicationsystem, a non-public intranet system, a public internet system, a localarea network (LAN), or a wide area network (WAN).
 11. A method forexecution by a computing device, the method comprising: identifying, viaan interface of the computing device that is configured to interface andcommunicate with a dispersed or distributed storage network (DSN), anencoded data slice (EDS) to be rebuilt, wherein a data object issegmented into a plurality of data segments, wherein a data segment isdispersed storage error encoded to produce a set of encoded data slices(EDSs), which includes the EDS, wherein a set of storage units (SUs) ofthe DSN stores the set of EDSs, and wherein a first storage unit (SU) ofthe set of SUs is assigned to store the EDS; determining whether the setof EDSs is stored in an encrypted section of a vault or within anunencrypted section of the vault; based on a first determination thatthe set of EDSs is stored in the encrypted section of the vault,enabling an unrestricted rebuilding process to rebuild the EDS; based ona second determination that the set of EDSs is stored in the unencryptedsection of the vault, determining whether the set of SUs have viewingrights; and based on a third determination that the set of SUs does nothave the viewing rights, enabling a restricted rebuilding process torebuild the EDS.
 12. The method of claim 11 further comprising: based ona fourth determination that the set of SUs does have the viewing rights,enabling the unrestricted rebuilding process to rebuild the EDS.
 13. Themethod of claim 11, wherein the data object comprises: an encryption keythat is used to encrypt data stored in the encrypted section of thevault, wherein the encryption key is dispersed storage error encodedinto a set of encoded key slices that is stored in the unencryptedsection of the vault supported by the set of SUs.
 14. The method ofclaim 11, wherein, wherein the set of EDSs is encrypted using anencryption key to produce an encrypted set of EDSs that is stored in theencrypted section of the vault supported by the set of SUs.
 15. Themethod of claim 11, wherein, wherein the set of EDSs is stored in theunencrypted section of the vault supported by the set of SUs.
 16. Themethod of claim 11, wherein, in accordance with the unrestrictedrebuilding process to rebuild the EDS, further comprising: sending sliceretrieval requests to a subset of SUs of the set of SUs, wherein thesubset of SUs excludes the first SU; in response to the slice retrievalrequests, receiving a subset of EDSs of the set of EDSs from the subsetof SUs; reconstructing the data segment from the subset of EDSs togenerate a reconstructed data segment; dispersed storage error encodingthe reconstructed data segment to produce a new set of EDSs; andselecting one of the new set of EDSs as a rebuilt EDS for the EDS. 17.The method of claim 11 further comprising: identifying a second EDS ofthe set of EDSs to be rebuilt; based on the third determination that theset of SUs does not have the viewing rights: enabling the restrictedrebuilding process to rebuild the EDS; and when the rebuilding of theEDS is complete, enabling the restricted rebuilding process to rebuildthe second EDS; and based on a fourth determination that the set of SUsdoes have the viewing rights, enabling the unrestricted rebuildingprocess to rebuild the EDS and the second EDS substantiallyconcurrently.
 18. The method of claim 11, wherein: a decode thresholdnumber of EDSs are needed to recover the data segment; a read thresholdnumber of EDSs provides for reconstruction of the data segment; a writethreshold number of EDSs provides for a successful storage of the set ofEDSs within the DSN; the set of EDSs is of pillar width and includes apillar number of EDSs; and each of the decode threshold number, the readthreshold number, and the write threshold number is less than the pillarnumber.
 19. The method of claim 11, wherein the computing deviceincludes a wireless smart phone, a laptop, a tablet, a personalcomputers (PC), a work station, or a video game device.
 20. The methodof claim 11, wherein the DSN includes at least one of a wirelesscommunication system, a wire lined communication system, a non-publicintranet system, a public internet system, a local area network (LAN),or a wide area network (WAN).